docs/174244: [patch] last one faq: why-kernel-big

[Bas Smeelen]

:) another "for information" removed

Index: en_US.ISO8859-1/books/faq/book.xml
===================================================================
--- en_US.ISO8859-1/books/faq/book.xml	(revision 40284)
+++ en_US.ISO8859-1/books/faq/book.xml	(working copy)
@@ -4114,18 +4114,30 @@
  	</question>
  
  	<answer>
-	  <para>Chances are, you compiled your kernel in <emphasis>debug
-	    mode</emphasis>.  Kernels built in debug mode contain many
-	    symbols that are used for debugging, thus greatly increasing
-	    the size of the kernel.  Note that there will be little or
-	    no performance decrease from running a debug kernel, and it
-	    is useful to keep one around in case of a system
-	    panic.</para>
+	  <para>GENERIC kernels shipped with &os; 7.x and later are compiled
+	    in <emphasis>debug mode</emphasis>. Kernels built in debug mode
+	    contain many symbols in separate files that are used for
+	    debugging, thus greatly increasing the size of
+	    <filename class="directory">/boot/kernel/</filename>.
+	    Note that there will be little or no performance decrease
+	    from running a debug kernel, and it is useful to keep one around
+	    in case of a system panic.</para>
  
-	  <para>However, if you are running low on disk space, or you
-	    simply do not want to run a debug kernel, make sure that
-	    both of the following are true:</para>
+	  <para>However, if you are running low on disk space, there are
+	    different options to reduce the size of
+	    <filename class="directory">/boot/kernel/</filename>.</para>
  
+	  <para>- If you do not want the symbol files to be installed,
+	    make sure you have the following line present in <filename>
+	    /etc/src.conf</filename>:
+
+	    <programlisting>WITHOUT_KERNEL_SYMBOLS=yes</programlisting>
+
+	    See &man.src.conf.5</para>
+
+	  <para>- If you simply do not want to build a debug kernel, make
+	    sure that both of the following are true:</para>
+
  	  <itemizedlist>
  	    <listitem>
  	      <para>You do not have a line in your kernel configuration
@@ -4142,9 +4154,30 @@
  
  	  <para>Either of the above settings will cause your kernel to
  	    be built in debug mode.  As long as you make sure you follow
-	    the steps above, you can build your kernel normally, and you
-	    should notice a fairly large size decrease; most kernels
-	    tend to be around 1.5 MB to 2 MB.</para>
+	    the steps above, you can build your kernel normally</para>
+
+	  <para>- If you want only the modules you use to be built
+	    and installed, make sure you have a line like below in
+	    <filename>/etc/make.conf</filename>:</para>
+
+	    <programlisting>MODULES_OVERRIDE= accf_http ipfw</programlisting>
+
+	  <para>Replace <emphasis>accf_httpd ipfw</emphasis> with a list
+	    of modules you need. Only these modules will be built. See
+	    <filename>/usr/share/examples/etc/make.conf</filename>. This
+	    does not only reduce the size of the kernel directory but
+	    also decreases the amount of time needed to build your kernel.
+	    </para>
+
+	  <para>- You can also remove unneeded devices from your kernel
+	    to further reduce the size. See <xref linkend="make-kernel"
+	    remap="another section"/></para>
+
+	  <para>To put any of these options into effect you will have
+	    to build and install your new kernel.</para>
+
+	  <para>Most kernels (<filename>/boot/kernel/kernel</filename>)
+	    tend to be around 12 MB to 16 MB.</para>
  	</answer>
        </qandaentry>